On-line gauges cut costs at extruded films factory

Smith and Nephew has cut costs dramatically by installing two NDC Infrared Engineering on-line gauges to provide closed-loop control of the film extrusion line at its extruded films factory near Hull

Global medical company Smith and Nephew has cut costs dramatically by installing two NDC Infrared Engineering on-line gauges to provide closed-loop control of the film extrusion line at its extruded films factory near Hull.

The 8000 series scanning weight gauge and automatic profile control system has improved set-up times by 50% and halved coat-weight variation tolerance.

Located at Gilberdyke, near Hull, Smith and Nephew manufactures a wide range of film and nets for the medical industry, such as breathable plasters, wound contact layers and bandages.

Two of NDC Infrared Engineering's scanning gamma backscatter weight gauges are installed on the Polyurethane film extrusion line.

The gauges scan across the width of the web to provide coat-weight measurement to the automatic profile control system.

Polyurethane film is extruded onto a paper carrier, which is 1.5 metres wide.

The first gauge measures the weight of the paper carrier.

The second gauge is positioned further down the line to measure total weight of the extruded film and paper together.

The first measurement subtracted from the second measurement provides total film weight.

The gauge data is fed back to the automatic profile control system, which adjusts the extrusion die accordingly.

Previously, coat-weight was measured by manually taking samples of film at the end of the process line.

The new system allows continuous weight measurement rather than just at roll ends and is not destructive.

Dr Robert Osman, New Technology Manager for Smith and Nephew Extruded Films explains: "NDC Infrared Engineering's technology has cut process costs and provided significant enhancements to our film extrusion line by reducing set-up times through the elimination of manual sampling, and by reducing coat-weight variation.

This has enabled us to increase the quality and consistency of our products.

We have also reduced scrap material by ?15k per year." NDC Infrared Engineering's 8000 series Gauging System with Automatic Profile Control (APC), provides Smith and Nephew with real-time measurement and control.

The automatic profile control system operates by changing the power level control or temperature feedback of the die.

The system is designed to make very fine adjustments to the die resulting in substantial reductions to profile variation without operator intervention.

NDC Infrared Engineering's 8000 series system can be applied to extrusion of sheet, film, oriented films and die coatings.

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